Polishing a work, e.g., semiconductor wafer, is performed by steps of: holding a work by a polishing head; pressing a surface of the work to be polished onto a surface of a polishing pad adhered on a polishing plate; and rotating the polishing plate and the polishing head with supplying slurry onto the polishing pad.
To improve accuracy of polishing the work, the polishing head can be tilted so as to move along a surface configuration (e.g., waviness) of the polishing pad (see PTL 1: JP-A-H06-126615, PTL 2: JP-A-H06-198561 and PTL 3: JP-A-2003-311607).
In PTL 1, a carrier (plate) is suspended from a head main body part through a tough and ring-shaped elastic plate (e.g., diaphragm), so that the carrier can be moved upward and downward and can be tilted. Further, a rotational force of the head main body part is transmitted to the carrier through the elastic plate or a ring-shaped elastic member (e.g., O-ring) provided between the head main body part and the carrier.
In PTL 2, a carrier (main body of a top ring) is tiltably supported, with respect to a head main body part (drive shaft), with a ball bearing. Further, a rotational force of the head main body part is transmitted to the carrier by a pin.
In PTL 3, a carrier (backing assembly) is suspended from a head main body part (housing) through a ring-shaped rolling diaphragm, so that the carrier can be moved upward and downward. Further, the carrier is tiltably supported by a gimbal mechanism having a flexure ring. A rotational force of the head main body part is transmitted to the carrier through the rolling diaphragm.
In PTL 1, the rotational force of the head main body part cannot be suitably transmitted to the carrier through the ring-shaped elastic member (e.g., O-ring) only. Actually, the elastic plate (e.g., diaphragm) mainly transmits the rotational force. Thus, the elastic plate must be composed of a tough material, but the carrier cannot be suitably tilted. Further, when the carrier follows surface configuration of the polishing pad, a load applied to a polishing pad from the carrier is varied due to tension of the tough elastic plate, so the polishing pad cannot be evenly pressed.
In PTL 3, the rotational force is transmitted to the carrier through the rolling diaphragm, the rolling diaphragm must have relatively high toughness capable of transmitting the rotational force, so the carrier cannot suitably tilt. Therefore, the polishing pad cannot be evenly pressed as well as PTL 1.
Further, in PTL 2, the carrier is tiltably supported by the tough ball bearing, so applying pressure from the carrier to a polishing pad cannot be precisely controlled.